Physics Colloquium with Daan Frenkel Department of Chemistry, University of Cambridge Is there still life in entropy? Entropy is a well-known, but not necessarily well-understood concept. Initially introduced in the context of thermodynamics, it was given a microscopic interpretation by Boltzmann and Gibbs in the context of equilibrium statistical mechanics. But more recently, entropy like quantities have been introduced to describe Daan Frenkel (1948) received his PhD in non-equilibrium systems. For instance, in an Physical Chemistry from the attempt to construct a Statistical Mechanics of University of Amsterdam in 1977. Powders, Sir Sam Edwards introduced the He was as a postdoc at UCLA (1977- concept of "granular entropy", defined as 1980). After that, he worked at Shell the logarithm of the number of distinct packings Research (Amsterdam), the Universities of of N granular particles in a fixed volume V. Utrecht and Amsterdam and at In 1989, the proposal was rather controversial the FOM Institute for Atomic and Molecular but much of the debate was sterile because Physics. In 2007, he was the granular entropy could not even be computed appointed 1968 Chair of Chemistry for systems as small as 20 particles - hardly a (Cambridge). Daan was Head of good approximation of the thermodynamic limit. Cambridge Chemistry Department from 2011 to 2015. In my talk I will describe how granular entropies He is a Foreign Member of the Royal Society of much larger systems can now be computed, (London), of the American using a novel algorithm. Interestingly, it turns out Academy of Arts & Sciences, of the US the definition of granular entropy will have to be National Academy of Sciences modified to guarantee that granular entropy is (USA), of the Netherlands Academy of extensive. Which brings us back to the Gibbs Sciences, of the Academia Europaea paradox and a dirty secret of colloid science. and of the World Academy of Sciences. He is an Honorary Fellow of Trinity College Cambridge. He received numerous international prizes (including the 20161 IUPAP Thursday, February 27, 2020 Boltzmann Medal, the Aneesur Rahman Prize In of the APS and the Alder-CECAM Prize of the EPS). Lewis Lab. 316 At He has published some 500 papers and two 4:25PM books. .